Horton

Re: BUG #14941: Vacuum crashes

Nathan Bossart <bossartn@amazon.com>

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From: "Bossart, Nathan" <bossartn@amazon.com>
To: Michael Paquier <michael.paquier@gmail.com>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Lyes Ameddah <lyes.amd@gmail.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, "pgsql-bugs@postgresql.org" <pgsql-bugs@postgresql.org>
Date: 2018-01-10T17:26:43Z
Lists: pgsql-bugs, pgsql-hackers

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On 1/9/18, 8:54 PM, "Michael Paquier" <michael.paquier@gmail.com> wrote:
> Backpedalling a bit on this point and coming back to this message from
> Tom (https://www.postgresql.org/message-id/28748.1507071576%40sss.pgh.pa.us)
> which you just cited. Why do we actually need to issue any WARNING
> messages for unlisted relations? Contrary to what Sawada-san complained
> upthread, it looks sane to me to not log anything if a relation is not
> explicitely listed. So you should not get any warnings for a
> database-wide VACUUM if a relation is dropped while the thing is
> running, and what you proposed initially in
> https://www.postgresql.org/message-id/D3FC73E2-9B1A-4DB4-8180-55F57D116B4E@amazon.com
> is more simple, does not need to worry about any kind of timing issues,
> and is consistent with autovacuum.

Right.  I don't have a terribly strong opinion either way.  I think the
counter-argument is that logging skipped relations might provide
valuable feedback to users.  If I ran a database-wide VACUUM and a
relation was skipped due to lock contention, it might be nice to know
that so I can handle the relation individually.

Perhaps any logging changes for VACOPT_NOWAIT could be handled in a
separate thread.  For now, I've updated 0003 to remove the logging
changes.

Nathan

Commits

  1. Add option SKIP_LOCKED to VACUUM and ANALYZE

  2. Rename VACOPT_NOWAIT to VACOPT_SKIP_LOCKED

  3. Add parenthesized options syntax for ANALYZE.

  4. Don't allow VACUUM VERBOSE ANALYZE VERBOSE.

  5. Fix inadequate locking during get_rel_oids().

  6. Avoid having autovacuum workers wait for relation locks.